Today, electric vehicles are the solution to green transportation. However, compared with the traditional cars that have been continuously used and developed in the last century, electric vehicles are still far from mature, especially in terms of fire safety. Safety accidents related to electric vehicle batteries occur frequently, and the number increases sharply year by year. Most accidents have been linked to fires in EV battery packs caused by thermal runaway from the current charging mode, known as fast-charging technology. Such safety concerns have prevented electric vehicles from becoming a dominant transportation system.
Thermal runaway is a state that occurs when the temperature of a battery reaches a critical value, causing the reaction rate of an exothermic reaction to increase in temperature, which in turn causes the reaction rate to increase further. It is triggered due to mechanical, electrical and thermal abuse. Mechanical abuse is due to physical accidents, collisions or penetrations. Electrical abuse constitutes overcharging and overdischarging of batteries. Likewise, thermal abuse includes operating temperatures, i.e. hot and cold climates. All three abuse scenarios lead to an internal short circuit in the battery, which can spread dangerous thermal runaway and release toxic gases and cause a fatal explosion. Other possible causes of EV fires are poor battery thermal management systems, poor battery quality, improper battery pack assembly, manufacturing defects, choice of battery geometry, battery gaps, and battery alignment. All of these reasons also contribute to the frequent EV fires. In addition, fast charging can speed up battery degradation, which can affect the lifespan and performance of electric vehicles.
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Also, the resurgence of thermal runaway is a bigger concern today. Electric vehicles will re-ignite after a few hours, which is uncontrollable and directly affects the safety of life and property. All these reasons clearly point to the need for proper fault detection and early warning of the risks and hazards associated with the occurrence of thermal runaway in EVs.
Besides recharging the battery instantly, there is another way to refuel a depleted battery. This can be done by replacing the discharged battery with a freshly charged one. This is known as battery swapping. India has only focused on two- and three-wheel battery replacements by manual replacement, while recently the US and China have started robotic replacements, which are safer and work faster. The whole operation can be completed in just 3-5 minutes, which is less time than the fast charging technology takes. The battery swap station will ensure the availability of rechargeable batteries and provide battery as a service (BaaS). Charging operations will be the responsibility of the service provider, and proper charging and maintenance operations can prolong battery life and thus provide better performance for electric vehicles. In 2022, India released a draft exchange policy highlighting the implementation of this new technology as well as additional safety and testing standards, standardization and operational planning in the coming years.
This new battery-swapping technology could reduce fatal electric vehicle fires and ensure safety. This alternative also addresses customer concerns by reducing refueling times, lowering operating costs, extending service life and facilitating battery recycling for a greener environment.
So, being a smart customer, how do you choose to charge your electric car? Deadly fast charging or safer battery replacement?
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